U.S. patent application number 14/651631 was filed with the patent office on 2015-11-12 for method and user equipment for performing d2d service in wireless communication system.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is INDUSTRY-ACADEMIC COOPERATION FOUNDATION YONSEL UNIVERSITY, LG ELECTRONICS INC.. Invention is credited to Jaehoon CHUNG, Genebeck HAHN, Eunjong LEE, Jangwon LEE, Heetae ROH.
Application Number | 20150327048 14/651631 |
Document ID | / |
Family ID | 50934561 |
Filed Date | 2015-11-12 |
United States Patent
Application |
20150327048 |
Kind Code |
A1 |
LEE; Eunjong ; et
al. |
November 12, 2015 |
METHOD AND USER EQUIPMENT FOR PERFORMING D2D SERVICE IN WIRELESS
COMMUNICATION SYSTEM
Abstract
A method and user equipment (UE) for performing device-to-device
(D2D) communication in a wireless communication system is
disclosed. The method of performing D2D communication by a D2D UE
includes informing a mobility management entity (MME) about a first
identifier (ID) of a target UE of D2D communication, receiving
information regarding a second ID and a D2D peer discovery section,
corresponding to the target UE, determining whether D2D
communication with the target UE is possible using the received
information, requesting the D2D communication with the target UE to
the MME when the D2D communication with the target UE is possible,
and receiving a D2D link ID allocated to the D2D link with the
target UE from a base station (BS) receiving approval of
communication of the MME.
Inventors: |
LEE; Eunjong; (Anyang-si,
Gyeonggi-do, KR) ; HAHN; Genebeck; (Anyang-si,
Gyeonggi-do, KR) ; ROH; Heetae; (Seongnam-si,
Gyeonggi-do, KR) ; LEE; Jangwon; (Seoul, KR) ;
CHUNG; Jaehoon; (Anyang-si, Gyeonggi-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC.
INDUSTRY-ACADEMIC COOPERATION FOUNDATION YONSEL UNIVERSITY |
Seoul
Seoul |
|
KR
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
INDUSTRY-ACADEMIC COOPERATION FOUNDATION YONSEL
UNIVERSITY
Seoul
KR
|
Family ID: |
50934561 |
Appl. No.: |
14/651631 |
Filed: |
September 13, 2013 |
PCT Filed: |
September 13, 2013 |
PCT NO: |
PCT/KR2013/008294 |
371 Date: |
June 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61736498 |
Dec 12, 2012 |
|
|
|
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 72/0406 20130101;
H04W 4/70 20180201; H04W 76/14 20180201; H04W 92/18 20130101; H04W
8/005 20130101 |
International
Class: |
H04W 8/00 20060101
H04W008/00; H04W 72/04 20060101 H04W072/04; H04W 76/02 20060101
H04W076/02; H04W 4/00 20060101 H04W004/00 |
Claims
1. A method for performing device-to-device (D2D) communication by
a D2D user equipment (UE) in a wireless communication system, the
method comprising: informing a mobility management entity (MME)
about a first identifier (ID) of a target UE of D2D communication;
receiving information regarding a second ID and a D2D peer
discovery section, corresponding to the target UE; determining
whether D2D communication with the target UE is possible using the
received information; requesting the D2D communication with the
target UE to the MME when the D2D communication with the target UE
is possible; and receiving a D2D link ID allocated to the D2D link
with the target UE from a base station (BS) receiving approval of
communication of the MME.
2. The method according to claim 1, wherein the D2D peer discovery
section comprises a section for transmitting a D2D peer discovery
message and a section for receiving a D2D peer reply message, and
wherein the determining comprises: transmitting the D2D peer
discovery message to the target UE in the section for transmitting
the D2D peer discovery message, receiving the D2D peer reply
message from the target UE in the section for receiving the D2D
peer reply message, and determining whether the D2D communication
with the target UE is possible.
3. The method according to claim 2, wherein the D2D peer discovery
message and the D2D peer reply message are transmitted via a
control channel allocated to a specific subframe.
4. The method according to claim 3, wherein the control channel is
a dedicated channel for a UE for performing D2D communication, and
wherein the control channel is allocated to a specific location of
a physical uplink shared channel (PUSCH) resources or a physical
downlink shared channel (PDSCH) resources, and a resource block for
the control channel is dropped when data to be transmitted through
the control channel is not present.
5. The method according to claim 1, wherein the first ID comprises
a unique phone number of the target UE, and wherein the second ID
comprises a global unique temporary identifier (GUTI).
6. A method for performing device-to-device (D2D) communication by
a D2D user equipment (UE) in a wireless communication system, the
method comprising: receiving information regarding a second ID and
a D2D peer discovery section, corresponding to the target UE from a
Base Station (BS); determining whether D2D communication with the
target UE is possible using the information; transmitting a result
of the determining to the BS; and receiving a D2D link ID allocated
to a D2D link with the target UE from the BS when the D2D
communication with the target UE is possible.
7. The method according to claim 6, wherein the D2D link ID
comprises a radio network temporary identifier (RNTI), and wherein
the method further comprises: performing the D2D communication with
the target UE by receiving resource information through the RNTI
when the RNTI allocated to the D2D link is received from the BS;
and performing the D2D communication with the target UE by
receiving resource information through a pre-allocated C-RNTI when
the RNTI allocated to the D2D link is not received from the BS.
8. The method according to claim 6, wherein the D2D peer discovery
section comprises a section for transmitting a D2D peer discovery
message and a section for receiving a D2D peer reply message, and
wherein the determining comprises: receiving information regarding
the ID of the target UE and the D2D discovery section of the target
UE from the BS, transmitting the D2D peer discovery message to the
target UE in the section for transmitting the D2D peer discovery
message, receiving the D2D peer reply message from the target UE in
the section for receiving the D2D peer reply message, and
determining whether the D2D communication with the target UE is
possible.
9. The method according to claim 7, wherein the D2D peer discovery
message and the D2D peer reply message are transmitted to a control
channel allocated to a specific subframe.
10. The method according to claim 7, wherein the control channel is
a dedicated channel for a UE for performing D2D communication, and
wherein the control channel is allocated to a specific location of
a physical uplink shared channel (PUSCH) resources or a physical
downlink shared channel (PDSCH) resources, and a resource block for
the control channel is dropped when data to be transmitted through
the control channel is not present.
11. A device-to-device (D2D) user equipment (UE) for performing D2D
communication in a wireless communication system, the D2D UE
comprising: a radio frequency (RF) module for transmitting a radio
signal; and a processor connected to the RF module, for controlling
the RF module, wherein the processor comprises to inform a mobility
management entity (MME) about a first identifier (ID) of a target
UE of D2D communication, to receive information regarding a second
ID and a D2D peer discovery section, corresponding to the target
UE, to determine whether D2D communication with the target UE is
possible using the received information, to request the D2D
communication with the target UE to the MME when the D2D
communication with the target UE is possible and to receive a D2D
link ID allocated to the D2D link with the target UE from a base
station (BS) receiving approval of communication of the MME.
12. The D2D UE according to claim 11, wherein the D2D peer
discovery section comprises a section for transmitting a D2D peer
discovery message and a section for receiving a D2D peer reply
message, and wherein the processor further comprises to transmit
the D2D peer discovery message to the target UE in the section for
transmitting the D2D peer discovery message, to receive the D2D
peer reply message from the target UE in the section for receiving
the D2D peer reply message, and to determine whether the D2D
communication with the target UE is possible.
13. The D2D UE according to claim 11, wherein the first ID
comprises a unique phone number of the target UE, and wherein the
second ID comprises a global unique temporary identifier
(GUTI).
14. A device-to-device (D2D) user equipment (UE) for performing D2D
communication in a wireless communication system, the D2D UE
comprising: a radio frequency (RF) module for transmitting a radio
signal; and a processor connected to the RF module, for controlling
the RF module, wherein the processor comprises to receive
information regarding a second ID and a D2D peer discovery section,
corresponding to the target UE from a Base Station (BS), to
determine whether D2D communication with the target UE is possible
using the information, to transmit a result of the determining to
the BS, and to receive a D2D link ID allocated to a D2D link with
the target UE from the BS when the D2D communication with the
target UE is possible.
15. The D2D UE according to claim 14, wherein the D2D link ID
comprises a radio network temporary identifier (RNTI), and wherein
the processor further comprises to perform the D2D communication
with the target UE by receiving resource information through the
RNTI when the RNTI allocated to the D2D link is received from the
BS, and to perform the D2D communication with the target UE by
receiving resource information through a pre-allocated C-RNTI when
the RNTI allocated to the D2D link is not received from the BS.
16. The D2D UE according to claim 14, wherein the D2D peer
discovery section comprises a section for transmitting a D2D peer
discovery message and a section for receiving a D2D peer reply
message, and wherein the processor further comprises to transmit
the D2D peer discovery message to the target UE in the section for
transmitting the D2D peer discovery message, to receive the D2D
peer reply message from the target UE in the section for receiving
the D2D peer reply message, and to determine whether the D2D
communication with the target UE is possible.
Description
TECHNICAL FIELD
[0001] The present invention relates to wireless communication, and
more particularly, to a method and user equipment (UE) for
performing device-to-device (D2D) communication in a wireless
communication system.
BACKGROUND ART
[0002] Recently, as smart phones and tablet personal computers
(PCs) have entered widespread use and high-capacity multimedia
communication have been actively used, mobile traffic has
remarkably increased. In the future, it is expected that mobile
traffic will double every year. Most mobile traffic is transmitted
through a base station (BS). Thus, communication service carriers
are currently faced with serious problems in terms of network load.
Thus, in order to process increased traffic, communication carriers
have increased the number of network facilitates and have hurriedly
commercialized next-generation mobile communication standards for
effectively processing a large amount of traffic, such as mobile
world interoperability for microwave access (WiMAX) and long term
evolution (LTE). However, at this time, other solutions are needed
to cope with dramatic increase in wireless traffic in the
future.
[0003] Device-to-device (D2D) communication refers to distributed
communication technology for directly transmitting traffic between
adjacent nodes without infrastructures such as a BS. In a D2D
communication environment, each node such as portable user
equipment (UE) and so on searches for another UE that is physically
adjacent thereto, establishes a communication session therewith and
then transmits traffic. Likewise, D2D communication distributes
traffic concentrated at a BS to overcome traffic overload problems
and thus, has drawn attention as the next-generation mobile
communication technology successor to 4G. For this reason, standard
institutes such as the 3rd generation partnership project (3GPP),
the institute of electrical and electronic engineers (IEEE), and
the like have established D2D communication standards based on long
term evolution-A (LTE-A) or wireless-fidelity (Wi-Fi), and Qualcomm
and so on have also developed unique D2D communication
technologies.
[0004] D2D communication is predicted to create new communication
services as well as to increase performance of mobile communication
systems. In addition, D2D communication can support services such
as an adjacency-based social network service, a network game, or
the like and can overcome problems in terms of connection of UEs in
a shadow region using a D2D link as a relay. Thus, D2D technologies
are predicted to provide new services in various fields.
[0005] In reality, technology for communication between devices,
such as infrared communications, ZigBee, radio frequency
identification (RFID), and near field communication (NFC) based
thereon have already entered widespread use. However, these
technologies only support communication with one partner within a
very limited distance (about 1 m). Thus, strictly, it is difficult
to classify these technologies as D2D communication technologies
for distributing traffic of a BS.
[0006] Thus far, D2D communication has been described. However,
until now, details of network-assisted D2D for implementing D2D
communication with the help of a cellular network have not been
proposed.
DISCLOSURE
Technical Problem
[0007] An object of the present invention devised to solve the
problem lies in a method of performing device-to-device (D2D)
communication by a D2D user equipment (UE) in a wireless
communication system.
[0008] Another object of the present invention devised to solve the
problem lies in a D2D UE for performing D2D communication in a
wireless communication system.
[0009] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
Technical Solution
[0010] The object of the present invention can be achieved by
providing a method for performing device-to-device (D2D)
communication by a D2D user equipment (UE) in a wireless
communication system, the method including informing a mobility
management entity (MME) about a first identifier (ID) of a target
UE of D2D communication, receiving information regarding a second
ID and a D2D peer discovery section, corresponding to the first ID,
determining whether D2D communication with the target UE is
possible through the received information, requesting the D2D
communication with the target UE to the MME when the D2D
communication with the target UE is possible, and receiving a D2D
link ID allocated to a D2D link with the target UE from a base
station (BS) receiving approval of communication of the MME.
[0011] The D2D peer discovery section may include a section for
transmitting a D2D peer discovery message and a section for
receiving a D2D peer reply message, and the determining may include
transmitting the D2D peer discovery message to the target UE in the
section for transmitting the D2D peer discovery message, and
receiving the D2D peer reply message from the target UE in the
section for receiving the D2D peer reply message and determining
whether the D2D communication with the target UE is possible.
[0012] The D2D peer discovery message and the D2D peer reply
message may be transmitted to a control channel allocated to a
specific subframe.
[0013] The control channel may be a dedicated channel for a UE for
performing D2D communication, and the control channel may be
allocated to a specific location of a physical uplink shared
channel (PUSCH) or a physical downlink shared channel (PDSCH)
resources and a resource block for the control channel may not be
allocated when data to be transmitted through the control channel
is not present.
[0014] The first ID may include a unique phone number of the target
UE and the second ID may include a global unique temporary
identifier (GUTI).
[0015] In another aspect of the present invention, provided herein
is a method for performing device-to-device (D2D) communication by
a D2D user equipment (UE) in a wireless communication system, the
method including receiving information an identifier (ID) of a
target UE and a D2D discovery section from a base station (BS) and
determining whether D2D communication with the target UE is
possible, transmitting a result of the determining to the BS, and
receiving a D2D link ID allocated to a D2D link with the target UE
from the BS when the D2D communication with the target UE is
possible
[0016] The D2D link ID may include a radio network temporary
identifier (RNTI) and the method may further include receiving
resource information through the RNTI and performing the D2D
communication with the target UT when the RNTI allocated to the D2D
link is received from the BS, and receiving resource information
through a pre-allocated C-RNTI and performing cellular
communication when the RNTI allocated to the D2D link is not
received from the BS.
[0017] The D2D peer discovery section may include a section for
transmitting a D2D peer discovery message and a section for
receiving a D2D peer reply message, and the determining may include
receiving information regarding the ID of the target UE and the D2D
discovery section from the BS, transmitting the D2D peer discovery
message to the target UE in the section for transmitting the D2D
peer discovery message, and receiving the D2D peer reply message
from the target UE in the section for receiving the D2D peer reply
message and determining whether the D2D communication with the
target UE is possible.
[0018] The D2D peer discovery message and the D2D peer reply
message may be transmitted to a control channel allocated to a
specific subframe.
[0019] The control channel may be a dedicated channel for a UE for
performing D2D communication, and the control channel may be
allocated to a specific location of a physical uplink shared
channel (PUSCH) or a physical downlink shared channel (PDSCH)
resources, and a resource block for the control channel is not
allocated when data to be transmitted through the control channel
is not present.
[0020] In a further aspect of the present invention, provided
herein is a device-to-device (D2D) user equipment (UE) for
performing D2D communication in a wireless communication system,
the D2D UE including a radio frequency (RF) module for transmitting
a radio signal and a processor connected to the RF module, for
controlling the RF module, wherein the processor informs a mobility
management entity (MME) about a first identifier (ID) of a target
UE of D2D communication, receives information regarding a second ID
and a D2D peer discovery section, corresponding to the first ID,
determines whether D2D communication with the target UE is possible
through the received information, requests the D2D communication
with the target UE to the MME when the D2D communication with the
target UE is possible, and receives a D2D link ID allocated to a
D2D link with the target UE from a base station (BS) receiving
approval of communication of the MME
[0021] The D2D peer discovery section may include a section for
transmitting a D2D peer discovery message and a section for
receiving a D2D peer reply message, and the processor may transmit
the D2D peer discovery message to the target UE in the section for
transmitting the D2D peer discovery message, and receives the D2D
peer reply message from the target UE in the section for receiving
the D2D peer reply message and determines whether the D2D
communication with the target UE is possible.
[0022] The first ID may include a unique phone number of the target
UE and the second ID may include a global unique temporary
identifier (GUTI).
[0023] In a further aspect of the present invention, provided
herein is a device-to-device (D2D) user equipment (UE) for
performing D2D communication in a wireless communication system,
the D2D UE including a radio frequency (RF) module for transmitting
a radio signal, and a processor connected to the RF module, for
controlling the RF module, wherein the processor receives receiving
information an identifier (ID) of a target UE of D2D communication
and a D2D discovery section from a base station (BS) and
periodically determining whether D2D communication with the target.
UE is possible, transmits a result of the determining to the BS,
and receives a D2D link ID allocated to a D2D link with the target
UE from the BS when the D2D communication with the target UE is
possible.
[0024] The D2D link ID may include a radio network temporary
identifier (RNTI), and the processor may receive resource
information through the RNTI and performs the D2D communication
with the target UT when the RNTI allocated to the D2D link is
received from the BS, and receives resource information through a
pre-allocated C-RNTI and performs cellular communication when the
RNTI allocated to the D2D link is not received from the BS.
[0025] The D2D peer discovery section may include a section for
transmitting a D2D peer discovery message and a section for
receiving a D2D peer reply message, and the processor may transmit
the D2D peer discovery message to the target UE in the section for
transmitting the D2D peer discovery message, and receive the D2D
peer reply message from the target UE in the section for receiving
the D2D peer reply message and determine whether the D2D
communication with the target UE is possible.
Advantageous Effects
[0026] According to embodiments of the present invention, a target
user equipment (UE) of device-to-device (D2D) communication does
not have to transmit and receive data to and from a base station
(e-NodeB) and thus a UE requesting D2D communication can perform
D2D peer discovery regardless of a state of the target UE of the
D2D communication.
[0027] In addition, when the UE requesting the D2D communication
wants to acquire a list of target UEs of the D2D communication, a
state of the target UE does not have to be changed to a EPS
connection management (ECM) connected state, thereby reducing
unnecessary control signaling.
[0028] It will be appreciated by persons skilled in the art that
that the effects that could be achieved with the present invention
are not limited to what has been particularly described hereinabove
and other advantages of the present invention will be more clearly
understood from the following detailed description taken in
conjunction with the accompanying drawings.
DESCRIPTION OF DRAWINGS
[0029] The accompanying drawings, which are included to provide a
further understanding of the invention, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention.
[0030] In the drawings:
[0031] FIG. 1 is a block diagram illustrating structures of a base
station (Bs) and a user equipment (UE) in a wireless communication
system;
[0032] FIG. 2 is a flowchart of a method of performing
device-to-device (D2D) communication according to an embodiment of
the present invention;
[0033] FIGS. 3A and 3B are exemplary diagrams of a subframe in
which D2D communication is performed according to an embodiment of
the present invention;
[0034] FIG. 4 is a flowchart of a D2D peer discovery method
according to an embodiment of the present invention;
[0035] FIG. 5 is an exemplary diagram of a D2D peer discovery
method according to an embodiment of the present invention; and
[0036] FIG. 6 is a flowchart of a D2D communication method
according to an embodiment of the present invention.
BEST MODE
[0037] Reference will now be made in detail to the exemplary
embodiments of the present invention with reference to the
accompanying drawings. The detailed description, which will be
given below with reference to the accompanying drawings, is
intended to explain exemplary embodiments of the present invention,
rather than to show the only embodiments that may be implemented
according to the invention. The following detailed description
includes specific details in order to provide a thorough
understanding of the present invention. However, it will be
apparent to those skilled in the art that the present invention may
be practiced without such specific details. For example, the
following description focuses upon a case in which a mobile
communication system is a 3rd generation partnership project (3GPP)
long term evolution (LTE) system or a LTE-advanced (LTE-A) system.
However, the present technical features, aside from unique features
of 3GPP LTE and LTE-A may be applied to any other mobile
system.
[0038] In some instances, well-known structures and devices are
omitted in order to avoid obscuring the concepts of the present
invention and important functions of the structures and devices are
shown in block diagram form. The same reference numbers will be
used throughout the drawings to refer to the same or like
parts.
[0039] In addition, in the following description, it is assumed
that a user equipment (UE) refers to any mobile or fixed type
device of a user side, such as a user equipment, a mobile station
(MS), an advanced mobile station (AMS), etc., and that a base
station (BS) refers to any node of a network side that communicates
with the UE, such as a Node B, an e-NodeB, a base station, access
point (AP), etc. Throughout this specification, the technical
features of the present invention are described based on an
institute of electrical and electronic engineers (IEEE) 802.16
system, but may be applied to various other communication
systems.
[0040] In a mobile communication system, a UE may receive
information from a BS in downlink and transmit information in
uplink. The information transmitted or received by the UE may be
data and various control information. In addition, there are
various physical channels according to the type or use of the
information transmitted or received by the UE.
[0041] The following technical features can be applied to a variety
of wireless access technologies, for example, code division
multiple access (CDMA), frequency division multiple access (FDMA),
time division multiple access (TDMA), orthogonal frequency division
multiple access (OFDMA), single carrier frequency division multiple
access (SC-FDMA), and the like. CDMA may be embodied through radio
technology such as universal terrestrial radio access (UTRA) or
CDMA2000. TDMA may be embodied through radio technology such as
global system for mobile communication (GSM)/general packet radio
service (GPRS)/enhanced data rates for GSM evolution (EDGE), etc.
OFDMA may be embodied through radio technology such as IEEE 802.11
(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA),
and the like. UTRA is a part of a universal mobile
telecommunications system (UMTS). 3GPP LTE is a part of evolved
UMTS (E-UMTS), which uses E-UTRA. The 3GPP LTE employs OFDMA in
downlink and employs SC-FDMA in uplink. LTE advanced (LTE-A) is an
evolved version of 3GPP LTE.
[0042] It should be noted that specific terms disclosed in the
present invention are proposed for convenience of description and
better understanding of the present invention, and the use of these
specific terms may be changed to other formats within the technical
scope or spirit of the present invention.
[0043] FIG. 1 is a block diagram illustrating structures of a BS
105 and UE 110 in a wireless communication system 100.
[0044] Although, to simplify the wireless communication system 100,
one BS 105 and one UE 110 (which includes a device-to-device (D2D)
UE) are illustrated, the wireless communication system 100 may
include one or more BSs and/or one or more UEs.
[0045] Referring to FIG. 1, the BS 105 may include a transmission
(Tx) data processor 115, a symbol modulator 120, a transmitter 125,
a transceiving antenna 130, a processor 180, a memory 185, a
receiver 190, a symbol demodulator 195, and a reception (Rx) data
processor 197. In addition, the UE 110 may include a Tx data
processor 165, a symbol modulator 170, a transmitter 175, a
transceiving antenna 135, a processor 155, a memory 160, a receiver
140, a symbol demodulator 145, and an Rx data processor 150. The
transceiving antennas 130 and 135 are each illustrated as one
antenna in the BS 105 and the UE 110, respectively. However, the BS
105 and the UE 110 may each include a plurality of transceiving
antennas. Thus, the BS 105 and the UE 110 according to the present
invention supports multiple input multiple output (MIMO). In
addition, the BS 105 according to the present invention may support
both single user-MIMO (SU-MIMO) and multi user-MIMO (MU-MIMO)
schemes.
[0046] In downlink, the Tx data processor 115 receives traffic
data, formats and codes the received traffic data, and interleaves
and modulates (or symbol-maps) the coded traffic data to provide
modulation symbols ("data symbols"). The symbol modulator 120
receives and processes the data symbols and pilot symbols to
provide a stream of symbols.
[0047] The symbol modulator 120 multiplexes the data and pilot
symbols and transmits the data and pilot symbols to the transmitter
125. In this case, each of the transmitted symbols may be a data
symbol, a pilot symbol, or a signal value of zero. In each symbol
period, pilot symbols may be sequentially transmitted. The pilot
symbols may each be a frequency division multiplex (FDM) symbol, an
orthogonal frequency division multiplex (OFDM) symbol, a time
division multiplex (TDM) symbol, or a code division multiplex (CDM)
symbol.
[0048] The transmitter 125 receives the stream of symbols, converts
the stream into one or more analog signals, and further adjusts
(for example, amplifies, filters, and frequency-upconverts) the
analog signals to generate a downlink signal proper for
transmission via a radio channel. Then, the transceiving antenna
130 transmits the generated downlink signal.
[0049] In configuration of the UE 110, the transceiving antenna 135
receives the downlink signal from the BS 105 and provides the
received signal to the receiver 140. The receiver 140 adjusts (for
example, filters, amplifies, and frequency-downconverts) the
received signal, and digitizes the adjusted signal to acquire
samples. The symbol demodulator 145 demodulates the received pilot
symbols and provides the pilot symbols to the processor 155 for
channel estimation.
[0050] In addition, the symbol demodulator 145 receives a frequency
response estimated value for downlink from the processor 155,
data-demodulates the received data symbols to acquire data symbol
estimated values (which are estimation symbols of the transmitted
data symbols), and provides the data symbol estimated values to the
Rx data processor 150. The Rx data processor 150 demodulates (that
is, symbol-demaps), deinterleaves, and decodes the data symbol
estimated values to restore transmitted traffic data.
[0051] Processing by the symbol demodulator 145 and the Rx data
processor 150 is auxiliary to processing by the symbol modulator
120 and the Tx data processor 115 in the BS 105, respectively.
[0052] In the UE 110, in uplink, the Tx data processor 165
processes traffic data to provide data symbols. The symbol
modulator 170 may receive the data symbols and multiplex and
demodulate the data symbols to provide a stream of the symbols to
the transmitter 175. The transmitter 175 receives and processes the
stream of the symbols to generate an uplink signal. In addition,
the transceiving antenna 135 transmits the generated uplink signal
to the BS 105.
[0053] In the BS 105, the uplink signal is received from the UE 110
through the transceiving antenna 130, and the receiver 190 acquires
samples obtained by processing the received uplink signal. Then,
the symbol demodulator 195 processes the samples to provide pilot
symbols and a data symbol estimated value, which are received for
uplink. The Rx data processor 197 processes the data symbol
estimated value to restore the traffic data transmitted from the UE
110.
[0054] The processors 155 and 180 of the UE 110 and the BS 105
order (e.g., control, adjust, manage, etc.) operations in the UE
110 and the BS 105, respectively. The processors 155 and 180 may be
respectively connected to the memories 160 and 185 that store
program code and data. The memories 160 and 185 are connected to
the processor 180 and store an operating system, applications, and
general files.
[0055] According to the present invention, the processor 155 of the
UE 110 and the processor 180 of the BS 105 perform operations of
processing a signal and data except for a function of receiving or
transmitting a signal. For convenience of description, hereinafter,
the processors 155 and 180 will not be described in detail.
Although the processors 155 and 180 are not described in detail,
the processors 155 and 180 may perform a series of operations of
processing data, etc. instead of operations of receiving or
transmitting a signal.
[0056] The processors 155 and 180 may also be called controllers,
microcontrollers, microprocessors, microcomputers, etc. The
processors 155 and 180 may be embodied by hardware, firmware,
software, or a combination thereof. When embodiments of the present
invention are embodied using hardware, the processors 155 and 180
may include application specific integrated circuits (ASICs),
digital signal processors (DSPs), digital signal processing devices
(DSPDs), programmable logic devices (PLDs), field programmable gate
arrays (FPGAs), etc. which are configured to implement the present
invention.
[0057] When embodiments of the present invention are embodied using
firmware or software, the firmware or the software may be
configured to contain a module, process, or function used to
perform functions or operations according to the present invention.
The firmware or software configured to implement the present
invention may be included in the processors 155 and 180 or may be
stored in the memories 160 and 185 and driven by the processors 155
and 180.
[0058] Layers of a wireless interface protocol between a UE and a
wireless communication system (network) and between a BS and the
system may be classified into a first layer L1, a second layer L2,
and a third layer L3 based on the three lower layers of the open
systems interconnection (OSI) model that is well known in the field
of communications. A physical layer belongs to the first layer L1
and provides an information transmission service through a physical
channel. A radio resource control (RRC) layer belongs to the third
layer and provides control radio resources between the UE and the
network. The UE and the BS may exchange RRC messages through the
wireless communication network and the RRC layer.
[0059] In order to perform communication, a cellular UE present in
a cell in a cellular network or cellular communication accesses a
BS, receives control information for transmitting and receiving
data from the BS and then transmits and receives data to and from
the BS. That is, the cellular UE transmits and receives data
through the BS. Thus, in order to transmit data to another cellular
UE, the cellular UE transmits data thereof to the BS, and the BS
that receives the data transmits the received data to another
cellular UE. In order to transmit data to another cellular UE, one
cellular UE can transmit data only through the BS, and thus, the BS
schedules channels and resources for data transmission and
reception and transmits the scheduled information to each cellular
UE. Likewise, in order to perform communication between cellular
UEs through the BS, channels and resources for transmitting and
receiving data to and from the BS need to be allocated. However, in
device-to-device (D2D) communication, a D2D UE is configured to
directly transmit and receive a signal to the UE to which the D2D
UE wants to transmit data without a BS or a relay. Thus, it is
necessary to design channel and resource structures in order to
transmit and receive a signal without control of the BS. During
this design, it is necessary to prevent collision of allocated
resources and channels for conventional cellular UE when the D2D UE
operates in a cellular network.
[0060] D2D communication refers to a short distance communication
scheme for enabling direct communication between UEs without a BS
(e-NodeB) when the UEs are adjacent to each other. Compared with a
conventional communication scheme, a high data transmission rate
may be achieved. In addition, since communication is performed
without the e-NodeB, the number of UEs that can simultaneously use
the same resource can be increased, thereby increasing usage
efficiency of resources.
[0061] In a network supporting D2D communication, a cellular user
receiving a conventional general communication service and a D2D
user receiving a D2D service are present. Here, a mode for D2D
communication of the D2D user may include a cellular communication
mode in which communication between UEs is performed through a BS
as the cellular user does, and a D2D communication mode in which
communication between UEs is directly performed without the
e-NodeB.
[0062] In this case, in the cellular mode in which data is
transmitted through the e-NodeB, interference with another cellular
user should not be present, and thus, dedicated resources need to
be allocated. However, in the D2D communication mode for direct
communication between UEs, data may be transmitted by allocating
dedicated resources or sharing resources that are being used by
another cellular user.
[0063] The present invention proposes a form of D2D communication
that can be classified into two types.
[0064] 1. UE-Initiated D2D Mode.
[0065] A UE-initiated D2D mode is a type supporting only the D2D
communication mode and is used only by satisfying service
requirements of using only the D2D communication mode since a
higher data transmission rate is required than in the cellular
mode, for example, proximity gaming, high-volume data transmission,
or a service that is desired to be used only in the D2D
communication mode only by UE. According to the UE-initiated D2D
mode, a D2D service is initiated by request of the UE. Thus, a type
in which D2D communication is initiated by the UE is referred to as
the UE-initiated D2D mode.
[0066] In the UE-initiated D2D mode, the UE acquires a list of UEs
that can communicate with the UE via D2D peer discovery, requests
D2D service with a specific UE among the UEs to a network, is
allocated resources from the network, and performs D2D
communication. The UE-initiated D2D mode will be described with
reference to FIG. 2.
[0067] FIG. 2 is a flowchart of a method of performing D2D
communication according to an embodiment of the present
invention.
[0068] First, a D2D communication request UE (hereinafter, UE1)
that wants to request D2D communication informs a mobility
management entity (MME) of a list of D2D communication target UE
(hereinafter, UE2) of D2D communication (S101). In this case, the
UE1 transmits an identifier (ID) of the UE2. The ID is a unique
factor for identifying the UE2 around the world, and for example,
includes a phone number or a MAC address. The MME informs a BS of a
globally unique temporary identifier (GUTI) that is the ID of the
UE2, received from the UE1 (S103).
[0069] The BS informs the UE1 of an ID of the UE2, received from
MME, and transmits information regarding a D2D peer discovery
section corresponding to the UE2 (S105).
[0070] The UE1 performs D2D peer discovery in order to determine
whether D2D communication with the UE2 is possible (S107).
Operations S105 and S107 will be described below in detail.
[0071] When the UE1 determines that the D2D communication with the
UE2 is possible via operation S107, the UE1 requests the D2D
communication with the UE2 is possible to the MME (S109). In this
case, when the UE2 is in an ECM-idle state, the MME performs paging
on the UE2 (S110).
[0072] When the MME approves D2D communication between the UE1 and
the UE2, IDs of the UE1 and the UE2 are transmitted to an e-NodeB
(S111). In this case, the e-NodeB allocates radio network temporary
identifies (RNTIs) to D2D links between the UE1 and the UE2 (S113)
and informs the UE1 and UE2 of the RNTIs, respectively (S115).
[0073] The e-NodeB may allocate resources to the D2D link through
the corresponding RNTI such that the UE1 and the UE2 may perform
D2D communication on each other.
[0074] The aforementioned operations S105 and S107 will now be
described in more detail. With regard to D2D peer discovery, a D2D
UE performing D2D communication needs to pre-check presence of
adjacent D2D UEs that can transmit and receive data in order to
transmit data to another D2D UE via D2D communication, and to this
end, the D2D peer discovery is performed.
[0075] The present invention proposes a method of enabling the UE1
to perform D2D peer discovery regardless of an ECM-idle state or
ECM-connected state of the UE1. The D2D peer discovery may be
performed without changing a state of the UE2 to reduce unnecessary
control signaling. For detailed description, the proposed method is
described in terms of 3GPP LTE/LTE-A. However, the proposed method
may be applied to other communication systems (IEEE 802.16, WiMAX,
etc.).
[0076] FIGS. 3A and 3B are exemplary diagrams of a subframe in
which D2D communication is performed according to an embodiment of
the present invention. FIG. 3A is illustrated assuming that uplink
resources are allocated in a D2D communication mode and data is
transmitted and received through a physical uplink shared channel
(PUSCH). FIG. 3B is illustrated assuming that downlink resources
are allocated in a D2D communication mode and data is transmitted
and received via a physical downlink shared channel (PDSCH).
[0077] For D2D peer discovery, the following control channel is
defined. A physical uplink D2D control channel (PUDCCH) or a
physical downlink D2D control channel (PDDCCH) are periodically
allocated like a conventional control channel, and an e-NodeB
informs all UEs about information (the size of resource block
allocated to the PDUCCH or the PDDCCH, a resource block index
(e.g., an physical resource index (PRB)), transmission start time,
and a transmission period) regarding the PDUCCH (or the PDDCCH)
through system information.
[0078] Referring to FIG. 3A, the PUDCCH is divided into a section
for transmitting a D2D peer discovery message and a section for
receiving a D2D peer reply message. Any UE that can perform D2D
communication may monitor the section for transmitting the D2D peer
discovery message. The PUDCCH may be allocated to a specific
location of resources of the PUSCH. In order to increase usage
efficiency of resources, when data to be transmitted through the
PUDCCH is not present, a resource block may not be allocated for
the PUDCCH and may be allocated for uplink data transmission of
other UEs.
[0079] From this point of view, FIG. 3B is the same as FIG. 3A. The
PDDCCH is also divided into a section for transmitting a D2D peer
discovery message and a section for receiving a D2D peer reply
message. Any UE that can perform D2D communication may monitor the
section for transmitting the D2D peer discovery message. The PDDCCH
may be allocated to a specific location of resources of the PDSCH.
In order to increase usage efficiency of resources, when data to be
transmitted through the PDDCCH is not present, a resource block may
not be allocated to the PDDCCH and may be allocated for uplink data
transmission of other UEs.
[0080] FIG. 4 is a flowchart of a D2D peer discovery method
according to an embodiment of the present invention.
[0081] First, a UE1 receives a UE2 ID and the D2D peer discovery
section of the UE2 from a BS (S201).
[0082] The D2D peer discovery section may include the section for
transmitting the D2D peer discovery message and the section for
receiving the D2D peer reply message.
[0083] The UE1 transmits a D2D peer discovery message through a
resource block A or A' for transmitting the D2D peer discovery
message of the PUDCCH (or the PDDCCH) in the D2D peer discovery
message transmission section received in operation S201 (S203).
[0084] In this case, since any UE that can perform D2D
communication monitors the PUDCCH (or the PDDCCH), the UE2 may
receive the D2D peer discovery message (S205). The UE2 receiving
the D2D peer discovery message transmits the D2D peer reply message
through a resource block B or B' for transmitting the D2D peer
reply message of the PUDCCH (or the PDDCCH) (S207). When the UE1
receives the D2D peer reply message (S209), the UE1 determines that
D2D communication with the UE2 transmitting the D2D peer reply
message is possible (S211).
[0085] FIG. 5 is an exemplary diagram of a D2D peer discovery
method according to an embodiment of the present invention.
[0086] Referring to FIG. 5 in relation to FIG. 4, operation S201
corresponds to time X. The UE1 receives the UE2 ID and the D2D peer
discovery section of the UE2 from the BS at the time X. In this
case, transmission time of the D2D peer discovery message indicates
time Y. The UE2 monitors the PUDCCH (or the PDDCCH) at the time Y
and thus may receive the D2D peer discovery message (S205). In
addition, the UE2 transmits the D2D peer reply message at time Z
(S207).
[0087] 2. MME-Initiated D2D Mode.
[0088] An MME-initiated D2D mode is a communication mode in which a
network can dynamically select an optimal D2D mode according to a
distance between UEs and a channel situation. In this regard, a D2D
service may be selected according to request of a mobility
management entity (MME). That is, when the MME that manages the
mobility of UEs compares cell IDs in which the UEs are present, if
the UEs are present in the same cell, the MME initiates D2D
communication. This is referred to as the MME-initiated D2D mode.
According to the MME-initiated D2D mode, when UEs that are
communicating with each other are close to each other so as to
perform D2D communication based on location information of the
corresponding UEs, the MME periodically performs D2D peer
discovery. In this case, when D2D communication can be performed, a
D2D communication mode is used but otherwise resources are
allocated so as to perform communication in a cellular mode. The
MME-initiated D2D mode will be described with reference to FIG.
6.
[0089] FIG. 6 is a flowchart of a D2D communication method
according to an embodiment of the present invention.
[0090] When an MME determines that a D2D communication mode is
possible based on location information of UEs that communicate with
each other, the MME informs a BS about IDs of corresponding UEs,
that is, GUTI (S301). Various methods of determining possibility of
the D2D communication mode by the MME may be used. For example,
when the UEs are positioned in the same cell, the MME may determine
that the D2D communication mode is possible.
[0091] The UE1 periodically determines whether D2D communication
with the UE2 is possible (S303). Operation S303 is the same as the
aforementioned D2D peer discovery process.
[0092] First, the UE1 receives the transmission time (time Y) of
the UE2 ID and the D2D peer discovery message of the UE2 from a BS
(S201). The UE1 transmits the D2D peer discovery message of the
PUDCCH (or the PDDCCH) through the resource block A or A' for
transmitting the D2D peer discovery message at the transmission
time (time Y) received in operation S201 (S203). In this case, any
UE that can perform D2D communication monitors the PUDCCH (or the
PDDCCH), and thus, the UE2 may receive the D2D peer discovery
message (S205). The UE2 that receives the D2D peer discovery
message transmits the D2D peer reply message through the resource
block B or B' for transmitting the D2D peer reply message of the
PUDCCH (or the PDDCCH) at time Z (S207). When the UE1 receives the
D2D peer reply message (S209), the UE1 determines that D2D
communication with the UE2 transmitting the D2D peer reply message
is possible (S211).
[0093] The UE1 informs the the BS of a result obtained in operation
S211 (S305). When the UE1 informs the BS that D2D communication
with the UE2 is possible, the BS allocates RNTIs to D2D links
between the UE1 and the UE2 and informs the UE1 and UE2 of the
RNTIs, respectively (S307). The RNTI information allocated to the
D2D links is not changed, and thus, a procedure of indicating the
RNTI is performed only once.
[0094] Thus, when the UE1 informs the BS that D2D communication
with the UE2 is possible, the BS allocates resource information to
the D2D links through the RNTIs (S309). When the UE1 informs the BS
that D2D communication with the UE2 is not possible, the BS
allocates resource information using C-RNTIs that are allocated to
the UE1 and the UE2, respectively (S311).
[0095] Operation S309 refers to a D2D communication mode between
the UE1 and the UE2. Operation S311 refers to a general cellular
mode. As described above, according to the MME-initiated D2D mode,
when UEs that are communicating with each other are close to each
other so as to perform D2D communication based on location
information of the corresponding UEs, the MME periodically performs
D2D peer discovery. In this case, when D2D communication can be
performed, a D2D communication mode is used but otherwise resources
are allocated so as to perform communication in a cellular
mode.
INDUSTRIAL APPLICABILITY
[0096] The present invention provides a method and user equipment
(UE) for performing or supporting device-to-device (D2D)
communication in a wireless communication system, which can be
industrially used in various communication systems such as 3GPP
LTE, LTE-A, IEEE 802, etc.
* * * * *